BAGHDAD, Iraq (AP) -- An insurgent suicide bomber detonated explosives strapped to his body Saturday, triggering a huge explosion at a gas station near a mosque south of Baghdad and killing at least 54 people. The attack capped a string of three major bombings over the past four days that killed at least 120.

Police Capt. Muthanna Khaled Ali and Dr. Adel Malallah of the Jumhuri General Hospital in Hillah, the provincial capital, said the gas station blast in Musayyib, about 40 miles south of Baghdad, killed 54 and wounded at least 82 others.

In Baghdad, the Interior Ministry put the casualty count at 51 dead and 82 wounded, but the report was believed based on a preliminary count.

Witnesses and police said the fuel tanker was moving slowly toward the pumps when an attacker ran to it and detonated his charge. A cluster of houses near the city-center gas station caught fire, the witnesses said. Gasoline stations in Iraq routinely include a number of small businesses selling tea, soft drinks and snacks and are often crowded with people.

Mussayib, a religiously mixed town along the Euphrates River, sits in the "triangle of death," an area so-named because of the large number of kidnappings and killings of Shiite Muslims traveling between Baghdad and the Shiite holy cities of Karbala and Najaf.

Earlier Saturday, the U.S. military announced it had filed charges against 11 soldiers for allegedly assaulting Iraqis detained during combat operations in the capital.

Three British soldiers from the 1st Battalion the Staffordshire Regiment were killed in a roadside bombing before dawn Saturday while on patrol in the city of Amarah, 180 miles southeast of Baghdad, British officials said. At lead nine Iraqi police died in other attacks across the country.

Iraqi police also arrested a would-be suicide bomber in Baghdad before he could detonate an explosive belt among a crowd mourning victims of an attack Wednesday that killed 27 people, mostly children, an official said. It was the second time a would-be suicide attacker was captured this week.